Born on August 24, 1869, in Fall River, Massachusetts, Morton's father, James Madison Morton Sr., was a prominent Boston lawyer who eventually served on the state supreme court.

[1] Morton was nominated by President William Howard Taft on August 9, 1912, to a seat on the United States District Court for the District of Massachusetts vacated by Judge Frederic Dodge.

He was confirmed by the United States Senate on August 12, 1912, and received his commission the same day.

[1] Morton was nominated by President Herbert Hoover on December 15, 1931, to a seat on the United States Court of Appeals for the First Circuit vacated by Judge George W. Anderson.

His service terminated on June 26, 1940, due to his death in Fall River.